Activity Workshop
 

Cryptography Puzzles

Introduction

In March 2016, the BBC website posted a series of 6 cryptography puzzles to test their readers' brains. You can find the original page here: http://www.bbc.co.uk/news/technology-34312697. The puzzles were not too difficult, but the explanations may not have gone into enough detail for some people. So here at the Activity Workshop, we're showing you a bit more about these puzzles and especially how you can solve puzzles like this yourself.

Along the way, apart from the fun of solving puzzles, you may learn something about cryptography, and you may learn something about python, too!

There were 6 puzzles, in roughly increasing complexity starting from the very simple.

Puzzle 1

You are given the following letter-translation table, and a series of coded questions with multiple-choice answers. You have to decode the questions and then answer them.

Letter table:
ABCDEFGHIJKLMNOPQRSTUVWXYZ
12@467810111214161718💾212223242526

And the questions:

1a: Where was the centre of @ ↑ 4 ☺ 2 18 ☺ 1 11 ☠ 14 7 during 23 23 B ?
Answers: HMGCC, MI5, Bletchley

1b: The man who designed the machine that @ 18 1 @ 11 ☺ 4 the ☺ 14 ☠ 7 ✈ 1 @ ↑ 4 ☺ was ?
Answers: Turing, Moore, Lorenz

1c: The fundamental 2 21 ☠ 12 4 ☠ 14 7 block of ☺ 12 ☺ @ ∞ 18 ↑ 14 ☠ @ devices is the ?
Answers: Algorithm, Transistor, Firmware

Puzzle 2

Assuming that puzzle 1 didn't cause you too many problems, it now gets slightly more difficult for puzzle 2. Here you're not given the lookup table, but only a sequence of numbers.

5 8 1 14 13 0 2 2 8 18 4 16 20 4 13 2 4

If you want, there's a hint available.

Puzzle 3

Along with a clue that this could have something to do with Julius Caesar and a cipher named after him, here is a sequence of characters for puzzle 3.

X S K L V V O H H Y L H V

If you still need help, there's a hint available.

Puzzle 4

This is slightly more difficult, as this puzzle uses symbols rather than letters or numbers. But it's actually not so different from the previous ones.

   
 · 
   
>
   
   
   
 1 
 8 
>
   
   
   
   
 · 
>
<
 · 
<·

,

   
   
 · 
   
   
 · 
   
 \/ 
 · 
 · 
 \/ 
   
<
 \/ 
   
   
   
 · 
   
   
   
 · 
   
 · 

   
   
 · 
   
   
 · 
 \/ 
   
>
 · 
   
 · 
   
   
 · 
   
>
   
   
   
 · 
   
 · 
 · 
   
/\
   
>
   
   
 · 
   
   
 · 
 · 
   
\/

 

As before, there's a hint available.

Puzzle 5

This time, there is just a list of numbers given, and at first glance it doesn't look like the same kind of substitution cipher as the previous ones. It's in the form of a question.

81, 1, 68, 59, 68, 86, 53, 76, 105, 53, 24, 22, 89, 5, 57, 68, 77, 50, 89, 81, 85, 4, 113, 71, 95, 86, 47, 44, 45, 33, 11, 64, 99, 12, 63, 10, 73, 8, 87, 52, 67, 68, 24, 72, 63, 25, 77, 6, 13, 3, 68, 57, 63, 101, 99, 60, 43, 14, 76, 88, 64, 47, 7, 53, 50, 99, 66, 76, 60, 22, 1, 99, 5, 47, 62, 53, 106, 8, 9, 81, 2, 68, 53, 75, 89, 52, 8, 25, 77, 27, 28, 113, 42, 4, 63, 75, 34, 63, 71, 63, 27, 52, 88, 76, 11, 17, 8, 11, 26, 77, 32, 113, 45, 13, 52, 77, 76, 11, 14, 13, 11, 66, 44, 63, 6, 115, 44, 37, 77, 7, 31, 6, 67, 63, 42, 77, 17, 13, 57, 84, 45, 8, 15, 63, 86, 43, 77, 68, 62, 74, 68, 23, 63, 92, 14, 68, 66, 53, 22, 52, 8, 24, 44, 68, 13, 81, 63, 18, 17, 53, 46, 72, 68, 44, 83, 39, 92, 62, 77, 28, 31, 52, 67, 63, 53, 28, 77, 43, 53, 13, 3, 3, 68, 65, 43, 63, 45, 34, 8, 26, 73, 67, 63, 68, 3, 63, 42, 68, 60, 65, 21, 4, 92, 73, 52, 74, 8, 57, 68, 65, 43, 63, 44, 38, 20, 13, 10, 52, 5, 63, 92, 50, 68, 66, 74, 67, 13, 81, 33, 75, 68, 81, 80, 63, 70 ?

You may well need a hint.

Puzzle 6

The sixth and final puzzle is split up into three rather unrelated parts.

6a

22 4a 72 27 65 72 20 6e 79 79 20 7a 6e 71 20 75 72 65 72 2e 20 56 27 7a 20 7a 6e 71 2e 20 4c 62 68 27 65 72 20 7a 6e 71 2e 22 20 22 55 62 6a 20 71 62 20 6c 62 68 20 78 61 62 6a 20 56 27 7a 20 7a 6e 71 3f 22 20 66 6e 76 71 20 4e 79 76 70 72 2e 20 22 4c 62 68 20 7a 68 66 67 20 6f 72 2c 22 20 66 6e 76 71 20 67 75 72 20 50 6e 67 2c 20 22 62 65 20 6c 62 68 20 6a 62 68 79 71 61 27 67 20 75 6e 69 72 20 70 62 7a 72 20 75 72 65 72 2e

There's also a not particularly useful hint.

6b

Here there appears to be some kind of numeric key 3 8 1 0 8 (or perhaps some permutation of it?) and the message itself:

1528262114512379959787446361667336365541049710185448490827733939750117578606349583824805 994668155766548948086204569455380471171904239315967452691

6c

This last puzzle is very graphical, and seems to show a kind of chessboard with black and white pieces on it:

 
   
   
   
  
   
  
  

The BBC used pawns for this, I upgraded them to bishops to make them a bit easier to see. But it doesn't make any difference to the cipher.

As before, you may need a hint for this one.

Finished?

If you're happy with your answers, you can check them over on the solutions page.